The present invention differs significantly from application Ser. No. 07/898,830, in that we have found that a horizontally fixed variable position mounting beam with quick height adjustment on either the rearward end or of the forward end of a rifle is necessary in some applications and is preferable to an adjustable tilting mounting beam. Other changes to allow positioning of the camera and to reduce manufacturing cost with minor versatility loss are included in this invention. These changes include use of stop pins to replace adjustable collars in assembly of the unit.